Murray, 41, is accused of having sex with the girl – who had been 16 for less than a month – after spiking her drink then later urging her to take the morning-after pill.

The court heard he had become friends with the girl when she was 15 and was playing truant from school.

The jury at Oxford Crown Court was told the alleged victim had spent a night at Murray's flat, where she said she woke up with her trousers around her knees.

In a police interview, she said Murray told her he had slept with her because he feared she may have fallen pregnant, and urged her to use emergency contraception to cover up his offence.

Tim Clarke, prosecuting, said Murray, sent her a text message hours after the alleged rape that said: "If you call the police and cry rape and that I spiked your Ribena, our friendship will be over. You can get a pill from Boots. James."

A video of the girl's police interview was shown to the court, in which she explained the two had become friends after meeting outside a shop near Murray's flat in Oxford.

In it, she said she had been invited to his home with friends, had been given alcohol, and allowed to play on Murray's computers and watch television.

After increasingly skipping lessons and staying overnight with Murray without telling her parents, a police officer visited her family home and told them about a relationship with an older man, she said.

During cross-examination, she said: "The police came round saying Jamie wasn't allowed to get in contact with me until I was 16."

On the night of the alleged rape, the court heard she had gone to Murray's flat at 9pm on a Friday in June 2010, and had watched films and used his computers until 2.30am.

She told police: "He gave me coke, then Ribena with mashed up ice cubes. I don't know if he put anything in it, but after drinking the Ribena I suddenly felt really tired all of a sudden."

After falling asleep alone, she said she woke up to find her trousers had been pulled down and Murray naked beside her on an inflatable bed.

"James said: 'Do you remember anything about last night?'" she said.

"I asked why. He said: 'Because I had sex with you when you were asleep'."

Asked how she felt about the incident, she said: "It's disgusting. Before, he seemed nice.

"He was funny, friendly, I could talk to him, we'd laugh about things on TV and joke about things generally. Now, I hate him."

Murray was arrested the following day and told police the pair were lovers for 10 days, having sex six times.

He is the second son of the Earl of Mansfield, 81, who is thought to have a fortune of £60 million, and Pamela, the Countess of Mansfield.